ShellCheck highlights several issues with the file - Shellcheck could be disabled, or issues resolved

[jamie-wearsafe]

It can be disabled by adding this line to the shell file:

# shellcheck disable=SC2292,SC2250,SC2086,SC1087,SC2248,SC2001,SC1007,SC2034

Issues can be seen by adding the script to the shellcheck online editor:

[dimo414]

Feel free to send a PR addressing the ShellCheck findings, but it would be good to limit the disable directives to specific offending lines where possible.

[rcaloras]

Should be addressed in #135